Wide band gap semiconductors, such as Aluminium-Gallium-Nitride (AlGaN) have a well known limitation of poor conductivity p-type or n-type creation, especially for p-type materials using an impurity atom substitutional doping method. At present the highest p-type acceptor density is achieved in p-GaN, with a substantial reduction in available hole concentrations with increasing band gap as the aluminium mole fraction is increased. This limits DUV LED development in relation to achieving electronic grade high n-type and p-type donor and acceptor concentrations in sufficiently wide band gap compositions of, for example, AlGaN, and more generally AlGaInN semiconductors.
DUV LEDs typically achieve light emission by advantageous spatial recombination of electrons and holes within a direct band gap crystalline structure. They fundamentally operate as a two electrical port device and are built from at least one of a p-i-n or p-n heterojunction diode with the emission region confined substantially to a region between the p-type and n-type regions. If the emission energy is smaller than the bandgap energy of at least one of the p-type and n-type cladding layers comprising the diode, then the photocarrier generated light can escape from within the device.